The present invention is based on an electromagnetic activation device in accordance with the teaching set forth herein. Such an activation device is known (German Auslegeschrift No. 12 47 793).
In such a known device the orientation of the armature plays a decisive role in regard to the costs as well as the degree of efficiency of the magnet. If formed with two magnetic poles, it is possible to obtain a comparatively small starting force and a large end force, since with a given magnetic circuit and excitation (amperage times number of coil turns) the power of the magnetic force has a squared relationship to the air gap. Therefore, when the air gap is twice as large, the magnetic force will only be 1/4 of that previously measured.
Therefore it is already known to use single pole arrangements (Swiss Pat. No. 367 022). However, very often differing radial forces are encountered here, so that such magnets are very difficult to control, i.e. to design.